Thirteen foreign journalists were detained and deported from the US last year, 12 of them from LAX.

As it happens, I've come close to being in the inverse situation: I've never gotten a business, journalism, or any other sort of visa for any of my visits to the UK, even though all of them have involved business meetings and research for my writings.

In 2002, I was invited -- and, more significantly, had my expenses paid -- by the BCC to participate in a television documentary investigating whether Northern Ireland was ready for foreign tourism. (I was followed around by a camera crew for several days, making it one of my more surreal travel experiences, a bit akin to appearing on a travel reality TV show.)

Changing planes at Heathrow Airport en route to Belfast, I made the mistake of telling the immigration inspector that the reason for my visit was for me to appear in a BBC production. What more "legitimate" cause could there be to come to the UK than an invitation from the Beeb, right? Wrong.

Instantly I realized it was a mistake. I was going to get paid for what I did in the UK. I was going to write about it . And I didn't have a business or work visa. After some questioning, my passport was stamped and I was admitted to the country -- with a look between me and the inspector that made perfectly clear that we both knew that I was breaking the rules, and that in the future I should keep my story straight: "I'm just a tourist".

Almost all countries ask arriving visitors, with or without visas, the purpose of their trip. Visits for business or employment of all types often requires a visa (even if tourists from and to the same countries don't need visas), and business visas are often subject to more intrusive application and approval procedures.

Many international business travellers don't bother to get visas or declare the business purpose of their trip, especially for brief visits for meetings or other activities for which they are not receiveing a salary in the destination country. Most of the time this is tolerated, with a wink and a nod, as long as business travellers play by the implicit rules: If you are entering a country as a tourist, don't say you are coming for business.

Business travellers who know they are breaking the rules, and taking a risk to avoid the nuisance and expense (and possibly delay of their trip) in order to get a business visa, are likely to grumble but take it in stride if they are caught in unexpected enforcement of business visa rules. You gamble, sometimes you get caught, and that's a cost of doing business that way.

The problem comes with people who don't realize that they are supposed to have a visa, or that they are supposed to say they are "just a tourist" when they arrive for business meetings without a visa. It's especially problematic if they assume that they have a "right" to cross borders, irrespective of visas or permits, an attitude which invariably prompts immigration officials to prove the sovereignty of their country by asserting their right to admit or deny whomever they please, without any obligation to give you an explanation of why.

Taking for granted a privilege that you don't really have, or that the other party to the interaction doesn't recognize, is a good way to get yourself in trouble anywhere in the world. (For more on the psychological and situational dymamics of border crossings, see the chapter on travel documents, "Papers, Please!" in The Practical Nomad: How To Travel Around The World .)

Professional journalists are engaged in business. I know of no international law suggesting that journalists are or should be exempt from entry requirements applicable to other business travellers. The USA, like many countries, has a separate category of visa for journalists than for some other types of businesses, mainly because of the different issues in establishing whether someone is a bona fide professional if they are a freelancer. That's a problem all journalist credentialling organizations face.

I think some of the anger from journalists at the USA starting to enforce the business visa law comes from the fact that accredited journalists from mainstream publications are accustomed to being exempt from many laws, including those about where they can go. They have "press passes" from the police to cross police lines, etc. So they assume, falsely, that there is a legal exemption that would let them cross borders freely, even when other people similarly situated need visas.

Don't get me wrong: I think there is a human right to travel freely, for work as well as pleasure. I don't think anyone ought to have to get permisison from a government to cross the artifical lines that governments have drawn on the maps of the world. But I also realize that that's not the current state of the law, at least in practice, and that one travels in the real world, as it is today.

"Congress shall make no law ... abridging ... the right of the people peaceably to assemble." (U.S. Constitution)

"Everyone has the right to freedom of movement and residence within the borders of each state. Everyone has the right to leave any country, including his own, and to return to his country." (Universal Declaration of Human Rights)

"Liberty of movement is an indispensable condition for the free development of a person." (United Nations Human Rights Committee)